Strain-based approach to investigate intergranular stress corrosion crack initiation on a smooth surface of austenitic stainless steel

This study investigated stress corrosion cracking (SCC) nucleation in sensitized austenitic stainless steel from the viewpoint of grain boundary (GB) character and strain at a GB where SCC can nucleate. Prior to SCC testing, normal and shear strains were measured on the surface of a specimen subjected to an initial strain of 1% via the digital image correlation (DIC) technique. Then, SCC testing was conducted under a constant load corresponding to the initial strain in a tetrathionate solution. After testing, crystal orientations in the specimen surface were measured by the electron backscattered diffraction (EBSD) technique. The relationship among crack initiation sites, GB character measured by EBSD, and strains measured by DIC is discussed. Stress corrosion cracks were found to be mainly initiated at random large-angle boundaries. The sites of intergranular crack initiation were characterized using the maximum normal strain along GBs, while the shear strain did not affect the crack initiation.